Staging is the process of finding out how far a cancer has spread. The outlook (prognosis) for people with cancer depends, to a large extent, on the cancer's stage. The stage of oral cavity and oropharyngeal cancers is one of the most important factors in choosing treatment.

Staging information is based on the results of the physical exam, endoscopy, and imaging tests (CT scan, MRI, chest x-ray, and/or PET scans), which are described in the section, "How are oral cavity and oropharyngeal cancers diagnosed?"

The TNM staging system

A staging system is a standard way for doctors to describe and summarize how far a patient's cancer has spread. The most common system used to describe the extent of oral cavity and oropharyngeal cancers is the TNM system of the American Joint Committee on Cancer (AJCC). The TNM system for staging describes 3 key pieces of information:

• T indicates the size of the main (primary) tumor and which, if any, tissues of the oral cavity or oropharynx it has spread to.

• N describes the extent of spread to nearby (regional) lymph nodes. Lymph nodes are small bean-shaped collections of immune system cells that are important in fighting infections. Cells from oral cavity or oropharyngeal cancers can travel to lymph nodes in the neck area.

• M indicates whether the cancer has spread (metastasized) to other organs of the body. (The most common site of spread is to the lungs. The next most common sites are the liver and bones.)

Numbers or letters appear after T, N, and M to provide details about each of these factors:

• The numbers 0 through 4 indicate increasing severity.
• The letter X means "cannot be assessed" because the information is not available.

T categories for cancers of the lip, oral cavity, and oropharynx:

• TX: primary tumor cannot be assessed; information not known
• T0: no evidence of primary tumor
• Tis: carcinoma in situ. This means the cancer is still within the epithelium (the top layer of cells lining the oral cavity and oropharynx) and has not yet grown into deeper layers of oral or oropharyngeal tissue
• T1: tumor is 2 cm (about ¾ inch) across or smaller
• T2: tumor is larger than 2 cm across, but smaller than 4 cm (about 1 ½ inch)
• T3: tumor is larger than 4 cm across
• T4 (for most oral cavity and oropharyngeal cancers): tumor is growing into nearby structures (such as bone, connective or muscle tissue of the neck, deep muscle of the tongue, skin, sinuses, or the larynx)
• T4 (for lip cancer): tumor is growing into nearby structures such as bones, floor of mouth, or skin of face

N categories:

• NX: nearby lymph nodes cannot be assessed; information not known
• N0: no spread to nearby lymph nodes
• N1: the cancer has spread to one lymph node on the same side of the head or neck as the primary tumor; this lymph node is smaller than 3 cm (about 1 ¼ inch) across
• N2 includes 3 subgroups:
  - N2a: the cancer has spread to one lymph node on the same side as the primary tumor; the lymph node larger than 3 cm across but smaller than 6 cm (about 2 ½ inches)
  - N2b: the cancer has spread to 2 or more lymph nodes on the same side as the primary tumor, but none are larger than 6 cm across
  - N2c: the cancer has spread to one or more lymph nodes on both sides of the neck or on the side opposite the primary tumor, but none are larger than 6 cm across
• N3: the cancer has spread to a lymph node that is larger than 6 cm across

M categories:

• MX: presence of distant spread cannot be assessed; information not known
• M0: no distant spread
• M1: the cancer has spread to distant sites outside the head and neck region (for example, the lungs)

Stage grouping

Once the T, N, and M categories have been assigned, this information is combined by a process called stage grouping to assign an overall stage of 0, I, II, III, or IV. Stage IV is further divided into A, B, and C.

Stage 0

Tis, N0, M0: The cancer is "in situ". It is still confined to the outer layer of oral or oropharyngeal tissue; it has not yet grown into a deeper layer and has not spread to nearby structures, lymph nodes, or distant sites.

Stage I

T1, N0, M0: The tumor is 2 cm (about ¾ inch) across or smaller and has not spread to nearby structures, lymph nodes, or distant sites.

Stage II

T2, N0, M0: The tumor is larger than 2 cm across but smaller than 4 cm and has not spread to nearby structures, lymph nodes, or distant sites.

Stage III

One of the following applies:

T3, N0, M0: The tumor is larger than 4 cm across, but it hasn't grown into nearby structures or spread to the lymph nodes or distant sites

T1, N1, M0 or T2, N1, M0 or T3, N1, M0: The tumor is any size and hasn't grown into nearby structures. It has spread to one lymph node on the same side of the head or neck, which is smaller than 3 cm across. The cancer hasn't spread to distant sites.

Stage IVA

One of the following applies:

T4, N0, M0 or T4, N1, M0: The tumor is growing into nearby structures (T4). It can be any size. It has either not spread to the lymph nodes (N0) or has spread to one lymph node, on the same side of the head or neck, which is smaller than 3 cm across (N1). The cancer hasn't spread to distant sites.

Any T, N2, M0: The tumor is any size and may or may not invade nearby structures. It has not spread to distant sites (M0). It has spread to one of the following:

• one lymph node one the same side of the head and neck that is between 3 and 6 cm across (N2a)
• one lymph node on the opposite side of the head and neck that is less than 6 cm across (N2b)
• 2 or more lymph nodes, all of which are smaller than 6 cm across. The lymph nodes can be on any side of the neck (N2c)

Stage IVB

Any T, N3, M0: The tumor is any size and may or may not grow into nearby structures. It has spread to one or more lymph nodes larger than 6 cm across, but it hasn't spread to distant sites.

Stage IVC

Any T, Any N, M1: The tumor is any size, and it may or may not have spread to lymph nodes. It has spread to distant sites, most commonly the lungs.

Recurrent (relapsed) cancer

This is not an actual stage in the TNM system. Recurrent (relapsed) disease means that the cancer has come back (recurred) after treatment. Recurrent oral cavity or oropharyngeal cancer may return in the mouth or throat (local recurrence), in the lymph nodes (regional relapse) or in another part of the body (distant recurrence, usually in the lungs).

Talk with your doctor, if you have any questions about the stage of your cancer or how it affects your treatment.

Relative 5-year survival rates, by stage

The following survival statistics come from the National Cancer Institute's SEER program. There are some important points to note about these numbers:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed. Many of these patients live much longer than 5 years after diagnosis. Five-year relative survival rates assume that some people will die of other causes and compares the observed survival of people with cancer with that expected for people without cancer. That means that relative survival only includes deaths from the cancer. They are considered to be a more accurate way to describe the outlook for patients with a particular type and stage of cancer.

• These numbers were derived from patients treated between 1988 and 2001. While they are among the most current numbers we have available, they represent people who were first diagnosed and treated many years ago. Improvements in treatment since then mean that the survival rates for people now being diagnosed with these cancers may be higher.

• While survival statistics can sometimes be useful as a general guide, they represent the outcomes of many people. They may not accurately represent any one person's prognosis. A number of other factors, including other tumor characteristics and a person's age and general health, can also affect outlook. Your doctor is likely to be a good source as to whether these numbers may apply to you, since he or she is familiar with your particular situation.

Lip

Tongue

Floor of the mouth

Gum and other mouth

Oropharynx and tonsil

* The numbers given are correct, but they indicate that for cancers of the oropharynx and tonsil, the 5-year survival for stages I, II, and III are essentially the same

Last Medical Review: 09/24/2009
Last Revised: 09/24/2009